“Thanks again for your great work. I am very picky about cleanliness, and I am very impressed by the attention to detail and thoroughness of the work you two did today. As I say, I am not easy to impress in this regard! I feel really lucky to have happen to come upon people who take such pride in their work! And thanks also for coming on such short notice. I’d be very happy to act as a reference for you if you wish. You have my email here, and my phone number. Feel free to provide these to someone who wants a reference..”